1. Field of the Invention
This invention relates to a method of erasure of x-ray images in such a manner as to eliminate the non-uniformities or ghosts arising from a previous image. More particularly, the invention relates to a method of erasure of an x-ray imaging device which uses high bias voltage during the image capture process.
2. Brief Description of the Prior Art
It is well known to use light to erase an image remaining on an x-ray plate. This is done for x-ray plates which use a stimulable phosphor medium as disclosed, for example, in U.S. Pat. No. 5,371,377 of Dec. 6, 1994, where light containing two distinct or separate emission bands is employed. This is also done for x-ray image capture panels where the photoconductive layer is made of a material such as amorphous selenium, lead oxide, thallium bromide, cadmium telluride, and the like which directly capture radiographic images as patterns of electrical charges, and where a high bias voltage is applied during the image capture process. Such a method is disclosed, for example, in U.S. Pat. No. 5,563,421 of Oct. 8, 1996 in conjunction with a special image capture panel, wherein the radiation sensitive layer is exposed to two uniform patterns of light, one after the other, in order to substantially eliminate residual electrical charges remaining in the photoconductive layer.
As mentioned in this U.S. Pat. No. 5,563,421, such electrical charges have also been minimized by the application of a reversed and decreasing electric field, however this involves multiple applications of such field.
Despite these various procedures, it has been found that non-uniformities or ghosts arising from a previous image still often remain on the x-ray imaging device.